There are some UA flights out of terminal 2, but no check-ins, so the signs tell you to go to terminal 1, which is fine, you can then easily walk to terminal 2. The signs are meant to help the lowest common denominator. A savvy traveler will know that an E/F gate means they can get off at 2 (if said traveler is already checked in). Should that be on the sign? No way. If that was on the signs, you'd have people ending up in terminal 2 who aren't already checked in. Not everyone leaving 5 and going to a domestic flight is checked in, and the tram also serves long term parking.